Data transmission and reception in a wireless communication system are carried out with frames in some cases. One frame is normally formed with a preamble, a header (a physical layer header), and a payload.
The preamble is formed with repetitions of a known signal sequence that is used in frame detection. The header stores the information necessary for demodulating and decoding the payload. The payload stores the current user data to be transmitted.
Since the information necessary for demodulating and decoding the payload is stored in the header, a reception device cannot correctly demodulate and decode the payload in a case where there is an error in the header.
Therefore, a transmission device normally encodes and modulates the header, using a scheme with performance similar to that of the scheme with the highest demodulation/decoding performance among the modulation schemes and the encoding schemes for the payload, or using a scheme with even higher performance than that.
The transmission device selects a modulation scheme and an encoding scheme suitable for the quality of the transmission path from among the schemes, and encodes and modulates the payload, using the selected schemes. Meanwhile, the transmission device encodes and modulates the header, using a predetermined scheme.